This project is an investigation into the mechanism and structure of the enzyme, Na, K-ATPase, that catalyses the ATP-dependent extrusion of sodium ions from neurons and other cells. Studies are proceeding along the following lines: (a) measurements of the transient (pre-steady state) kinetics of the phosphorylation and dephosphorylation reactions of the Na, K-ATPase; (b) experiments designed to define the relation of structure to function of different domains of the Na, K-ATPase molecule; (c) steady-state kinetic and lignand-binding studies directed toward elucidation of the mechanism of energy transfer from ATP hydrolysis to the ionophoric process.